Centrifugal pump



Oct. 31, 1944 DE WlTT E. YATES CENTRIFUGAL PUMP Filed Nov. 1, 1943Patented Oct. 31, 1944 is CENTRIFUGAL PUMP De Witt E. Yates, ChippewaFalls, Wfs., assignor to W. S. Darley & Company, Chicago, 111., a

corporation of Illinois Application November 1, 1943, Serial No. 508,5247 Claims. (Cl. 103,- -112) The present invention relates generallytocentrifugal pumps. More particularly the invention relates to that typeof centrifugal pump which is designed for displacing or pumping a liquidand as the primary or principal parts thereof embodies (1) a volutecasing having a cylindrical inlet in the central portion of the frontwall thereof and a tangential outlet in the portion of its side wallthat is of greatest or maximum radius; (2) a power driven shaft which isin axial alignment with, but of less diameter than, the inlet andextends into the central portion of the casing interior through astufling box on the central portion of the rear Wall of the easing; and(3) a closed variety, casing-enclosed impeller which comprises spacedapart front and rear shrouds and substantially radially extending bladesbetween the shrouds, is connected for drive by the shaft through themedium of a hub on the central portion of the rear shroud, has on thecentral portion of the front shroud a forwardly extending sealing ringthat fits within the cylindrical inlet in the front wall of the casing,and operates during drive thereof by the shaft to suck liquid into thecasing via the inlet and then, due to the actionof the blades, to flingthe liquid outwards under pressure so that it travels around the sidewall of the casing and is finally discharged through the tangentialdischarge.

In an elementary centrifugal pumpof this type the impeller and shaft,during pump operation, are subjected to undesirable end thrust in thedirection of the inlet in the front wall of the substantially free fromend thrust, is subject to several objections. In the first place, thecost of the pump is materially increased because of the addition of therearwardly extending sealing ring on the rear shroud and the necessityof drilling ports in the central portion of the rear shroud andmachining the cylindrical cavity in the rear wall of the casing.Secondly, the pump includes an additional-part which is subject to wearand may require replacement from time to time.

,Thirdly, the efliciency of the pump is reduced by reason of the factthat the space between the rearwardly extending sealing ring and theannular wall of the cylindrical cavity in the rear wall of the casing,the spacewithin the rearwardly extending sealing ring and the ports inthe central portion of the rear shroud of the impeller result in arepumping or recirculation of part casing due to the fact that the outersurface of the rear shroud is of greater area than the outer surface ofthe front shroud and hence the liquid under pressure in theclearancespace between the rear shroud of the impeller and the rear wallof the casing acts with greater force against the impeller than theliquid in the clearance space between the front shroud of the impellerand the front wall of the casing and urges the im- 'peller towards theinlet. It has heretofore been proposed to eliminate such end thrust byproviding the rear'shroud of the impeller with a rearwardly extendingsealing ring which is the same in diameter as the forwardly extendingsealing ring on the front shroud and fits within a cylindrical cavity inthe rear wall of the casing, and forming ports in the central portion ofthe rear shroud in order to establish communication between the interiorof the impeller and the space within the rearwardly extending sealingring. A pump embodying a rearwardly extending sealing ring and ports,although the impeller thereof is of the liquid that is pumped inconnection with drive of the impeller. Fourthly, foreign particles inthe liquid entering the inner portion of the impeller interior moverearwards through the ports and by lodging in the stufling box producewearing of the shaft by an abrasive action.

The primary object of the invention is to pro-: vide a centrifugal pumpwhich is more emcient than, eliminates the disadvantages or defectionsof, and is an improvement upon, previously designed pumps of likecharacter and is characterized by the fact thatit includes simple andnovel means whereby end thrust of the impeller and shaft is eliminatedwithout the necessity of em= ploying a rearwardly extending sealing ringon the rear shroud of the impeller together with ports in the innerportion of the rear shroud. In

general such means comprises stationary, radially extending ribs whichare formed on the inner surface of the front wall of the casing andserve, in connection with pump operation, to increase the pressureagainst the front shroud of the impeller by retarding rotation of theliquid under pressure that is in the clearance space between the frontshroud of the impeller and the front wall of the casing. It alsocomprises radially extending vanes which are. formed on the outersurface .of the rear shroud of the impeller and serve, in connectionwith pump operation, to re duce the pressure on the rear shroud byincreasing rotation of the liquid under pressure in the clearance spacebetween the rear shroud of the impeller and the rear wall of the casing.It is contemplated that in certain instances either the static-nary ribson the inner surface of the front wall of the casing or the radiallyextending vanes on the outer surface of the rear shroud of the nectedto, the rear walls.

impeller will suffice to produce the desired results so far as theelimination of end thrust of the impeller and shaft is concerned. It isalso contemplated that in other instances, such, for example, as inconnection with a pump having a comparatively large inlet in the frontwall of the casing, both the stationary ribs on the front wall of thecasing and the radially extending vanes on-the outer surface of the rearshroud of the impeller .may be employed in order completely to eliminateend thrust of the impeller and its drive shaft.

Another objectof the invention isto provide portion of the casing sidewall I that is of maximum radius and forms the pump outlet. The outerend of the nipple is provided with an internal screw thread in orderthat it may be connected to a pipe for conducting the pumped liquid tothe location or place desired. The rear wall 8 of the casing is formedseparately from the end wall 8 and embodies a rearwardly offset,outwardly extending, annular flange l8 which fits against the rearmargin ofthe end is removably secured in place by way of bolts ll.

- When the bolts are removed the rear wall 8 of a centrifugal pump whichis capable of being produced at a low and reasonable cost and in whichsimplicity of design or construction. is combined with long life.

Other objects of the invention and the various advantages andcharacteristics of the present centrifugal pump will be apparent from aconsideration of the following detailed description.

- impeller 8 and is driven by the casing may be separated from sidewalls in order to provide access to the interior oi the casing.

The shaft 5 serves as a driving medium for the any suitable drivingmeans; such, for example, as an internal combustion engine or anelectric motor.

- The invention consists in the several novel featureswhicharehereinafter set forth and are more particularly defined byclaims at the conclusion hereof. I v v In the drawing which accompaniesand forms a part of this specification or disclosure and in which likenumerals of reference denote corresponding parts throughout the severalviews:

Figure 1 is avertical longitudinal section of a centrifugal pumpembodying the invention;

Figure 2 is a vertical transverse'section taken on the line 2-4 ofFigure 1 and showing the rib formation which is applied to the innersurface of the front wall of the casing. and serves to in crease thepressure against the front shroud of the impeller by'retarding rotationof the liquid under pressure in the clearance space between the impellerand the front wall of the casing; and

Figure 3 is a rear view of the impeller illustrating in detail thearrangement and design of the radially extending vanes which are formedon the outer or' rear surface of the rear shroud of the impeller andserve to reduce the pressure on the rear shroud by increasing rotationof the liquid under pressure in the clearance space hetweenthe rearshroud of the impeller and the rear wall of the casing.

The centrifugal pump which is shown in the drawing constitutes thepreferred form or embodiment of the invention. It is designed todisplace or pump a liquid, such as water, andcomprises a volute casing4, a driving shaft 5 and an impeller 8. a

The casing 4 consists of a front wall I, a rear wall 8, and a side wall8 and is preferably in the form of a .composite casting.j The front wallI of the casing'is provided at the central portion thereof with anintegral forwardly extending sleeve-like part l8 and this defines acylindrical inlet II which leads from the casing exterior to the centralportion of the casing interior. A pipe I2 is attached by way of a screwthread iii to the outer end of the part l8 and serves to connect theinlet I l to the liquid body to be pumped. The rear wall 8 of the casing4 is disposed in spaced relation with the front wall 'I and embodies atits lower portion a bracket 14 whereby the pump as a whole may besecured to a supporting structure. The side wall 9 is volute' or spiralin form and extends between, and is con- A is connected to. and

'It is journalled in a bearing 18 on the upper portion of the bracket l4and is of materially less diameter than the cylindrical inlet 10 in thecentral portion of the front wall 1 of the casing. The front end of theshaft 5 extends through a stuiling box IE on the central portion of thecasing rear wall 8 and is provided at its extremity with a reduced stem5a which is centrally disposed in the interior of the casing. l

The impeller 8 is of the so-called closed variety and comprises acircular front shroud Zt'l, a circular rear shroud 2| and an annularseries of substantially radially extending blades 22 between the twoshrouds. -It is preferably in the form of a one-piece casting and islocated between, but in spaced relation-with, the front and rear wallsof the pump casing 4. The central portion of the front shroud 20embodies a circular opening and in addition a forwardly extendingsealing ring 23 which surrounds the opening; fits within the inner endof the sleevelike part in on the central portionof the front wall I ofthe casing and establishes communication between the cylindrical inletII and the terially less external diameter than the sealing ring 23 andis fixedly connected to the reduced stem 5a of the shaft 5 by way of acap screw 25.

- During operation of the pump liquid is drawn or outer margins of thefront and v sucked into the central portion of the impeller interior byway of the inlet II and the central opening in the front shroud and isthen flung outwards under pressure by the blades 22 against the end wall9 of the casing. Because of the shape or volute character of the sidewall the liquid travels around the side wall and then'is discharged viathe tangential discharge nipple l5. During operation of the pump thereis liquid under pressure in the clearance space between the rear shroud2| of the impeller and the, rear wall 8 of the casing and there is alsoliquid under pressure in the clearance space between the front shroud 20of the impeller andthe casing front wall 1. Due to the fact that theouter surface of the rear shroud is ofgreater area than the outersurface of the front shroud the liquid under pressure in the rearclearance space, i. e., the space between the rear shroud and the casingrear wall, acts with greater force on the impeller than the liquid underpressure in the front clearance space and tends to urge the impeller andshaft towards the inlet H. With a view of eliminating or counteractingend thrust of the impeller and wall and the front and k shaft the innersurface of the front wall 'I of the casing is provided with an integralrib structure 26 and the outer surface of the rear shroud 2| of theimpeller 8 is provided with an annular series of radially extendingvanes 21. The rib structure 28 on the. inner surface of the front wallof thepump casing comprises an annular series of equidistantly spacedradially extending ribs 28 and a circular rib 29. The radially extendingribs 28 project outwards from the inner end of the sleeve-like part '10and terminate adjacent the outer marginal portion of the inner surfaceof the front wall I of the casing. The circular rib 29 extends around,and is joined to the outer ends of, the radially extending ribs 28 asshown in Figure 2, and forms with such ribs wedge shaped pockets 30.When the pump is in operation the liquid under pressure in the clearancespace between the front shroud of the impeller and the front wall of thecasing tendsto swirl or rotate. The rib structure 26, however, retardsswirling of the liquid in the front clearance space and thus increasesthe pressure against the front shroud. By increasing the pressure of theliquid in the front clearance space against the front shroud end thrustof the impeller and shaft in the direcwall and an outlet at its outerportion: a drive shaft of less diameter than the inlet extending throughthe rear wall of the casing and arranged in axial relation with saidinlet; a closed variety impeller disposed in the casing and embodying afront shroud arranged in opposed and spaced relation with the casingfront wall and provided with a central opening in communication andsubstantially sealed relation with the inlet, a rear shroud arranged inopposed and spaced relation with the casing rear wall, having the outersurface thereof of greater area than the outer surthe casing operativeduring drive of the impeller tion of the inlet l l is counteractedt Thepockets serve to trap a portion of the liquid in the front clearancespace and thus coact with the rib structure 26 to retard rotation of theliquid in such clearance space and increase the pressure against thefront shroud of the impeller. The radially extending vanes 21 on theouter surface of the rear shroud 2| of the impeller are formedintegrally with the rear shroud and extend outwards fromthe rear end-ofthe hub 24. During operation of the pump the vanes 21 serve to increaserotation of the liquid under pressure in the clearance spacebetween therear shroud 2| of the impeller and the rear wall 8 of the pump casingand thus reduce the pressure against the rear shroud. By increasing thepressure against the front shroud 20 by the stationary rib structure 25and decreasing the pressure against the rear shroud by means of thevanes 21 end thrust of the impeller and drive shaft in the direction ofthe inlet I is effectively eliminated or counteracted. In certaininstances the desired results may be obtained by using either the ribstructure 26 or the vanes 2'1. In other cases, such, for example, as inconnection with a pump havinga comparatively large inlet, both the ribstructure 26 and the vanes 21 may be employed so as fully to 'coun-,

teract end thrust on the part of the impeller and its drive shaft.

The herein described centrifugal pump is characterized by extremely highefliciency by reason of the fact that end thrust of the impeller iseliminated while at the same time there is a minimum amount of repumpingof the liquid. It is further characterized by the fact that it is simplein design or construction and hence may be produced at a low cost. L D

The invention is not to be understood as re stricted to the details setforth since these may be modified within the scope of the appendedclaims without departing from the spirit and scope of the invention. x

Having thus described the invention what I claim as new and desire tosecure by Letters Patent is: I

1. A centrifugal pump adapted to displace or pump a liquid andcomprising a volute casing embodying spaced apart front and rear wallsand having an inlet in the central portion of its front to retardrotation of the liquid in the clearance space between the front shroudof the impeller and the front wall of the casing so as to increasepressure on the front shroud and thus counteract end thrust of theimpeller and shaft in the direc tion of the inlet.

" 2. A centrifugal pump adapted to displace or pump a liquid andcomprising a volute casing embodying spaced apart front and rear wallsand having an inlet in the central portion of its front wall and anoutlet at its outer portion; a drive shaft of less diameter than theinlet extending through the rear wall of the casing and arranged inaxial relation with said inlet; a closed variety impeller disposed inthe casing and embodying a front shroud arranged in opposed and spacedrela tron with the casing front wall and provided with a central openingin communication and substantially sealed relation with the inlet, arear shroud arranged in opposed and spaced relation with the casing rearwall, having the outer surface thereof of greater area than the outersurface of the front shroud, and provided at its central portion with ahub mounted fixedly on the shaft, and an annular series of substantiallyradially extending blades extending between the two shrouds and adaptedin connection with drive of the impeller to draw liquid into theimpeller interior via "said inlet and opening and to fling the liquidoutwards against the outer portion 'of'the' casing for discharge throughthe outlet; and a rib structure formed on the inner surfaceof the frontwall 01 the casing and operative during drive of the inrpeller to retardrotation of the liquid in the clearance space between the front shroudof the impeller and the front wall of the casing so as to increase pessure on the front shroud and thus counteract end thrust of theimpeller and shaft in the direction of the inlet;

3. A centrifugal pump adapted to displace or pump a liquid andcomprising a volute casing embodying spaced apart front and rear wallsand in axial relation with said inlet; a closed. variety impellerdisposed in the casing and embodying a front shroud arranged in opposedand spaced relation with the casing front wall and provided with acentral opening in communication and of the impeller to draw liquidinto'the impeller interior via said inlet and opening and to fling theliquid outwards against the outer portion of the casing for dischargethrough the outlet; and a rib structure formed on, and integrally with,the inner surface of the front wall, embodying an annular series ofsubstantially radial ribs, and operatlve during drive of the impeller toretard rota-r tion of the liquid in the clearance space between thefront shroud of the impeller and the front wall of the casing so as toincrease pressure on the front shroud and thus counteract endthrust ofthe impeller and shaft in the direction of the inlet.

4. A centrifugal pump adapted to displace or pump a liquid andcomprising a volute casing embodyingspaced apart front and rear wallsand having an inlet in the central portion of its front wall and anoutlet at its outer portion; a drive shaftof less diameter than theinlet extending through the rear wall of the casing and arranged inaxial relation with said inlet; a closed variety the outer surface ofthe front shroud, and provided at its central portion with a hub mountedfixedly on the shaft, and an annular series of substantially radiallyextending blades extending between the two shrouds and adapted inconnection with drive of the impeller to draw liquid inimpeller disposedin the casing and embodying a front shroud arranged in opposed andspaced relation with the casing front wall and provided with a centralopening in communication and substantially sealed relation with theinlet, a rear shroud arranged in opposed and spaced relation with thecasing rear wall, having the outer surface thereof of greater area thanthe outer surface of the front shroud, and provided at its centralportion with a hub mounted fixedly on the shaft, and an annular seriesof substantially radially extending blades extending between the twoshrouds and adapted in connection with drive of the impeller to drawliquid into the impeller interior via said inlet and opening and tofling the liquid outwards against the outer portion of the casing fordischarge through the outlet; and a rib structure on the inner face ofthe front wall of the casing embodying an annular series of radiallyextending ribs and a circular rib around the outer ends of theradially'extending ribs, and operative during drive of the impellmtoretard rotation of the liquid in the clearance space between the frontshroud of the impeller and the front wall of the casing so as toincrease pressure on the front to the impeller interior via said inletand opening and'to hing the liquid outwards against the outer portion ofthe casing for discharge through the outlet; and means on the outersurface of the rear shroud of the impeller extending inwards to thecentral portion of said rear shroud and operative during drive of theimpeller to increase rotation of the liquid in the clearance spacebetween the rear shroud of the impeller and the rear wall of the casingso as to decrease pressure on the rear shroud and thus counteract endthrust of the impeller and shaft in the direction of the inlet.

6. A centrifugal pump adapted to displace or pump a liquid andcomprising a voiute casing embodying spaced apart front and rear wallsand having an inlet in the central portion of its front wall and anoutlet at its outer portion; a drive shaft of less diameter than theinlet extending through the rear wall of the casing and arranged inaxial relation with said inlet; a closed variety impeller disposed inthe casing and embodying a front shroud arranged in opposed and spacedrelation with the casing front wall and provided .with a central openingin communication and substantially. sealed relation with the inlet, arear shroud arranged in opposed and spaced relation with the casing rearwall, having the out er surface thereof of greater area than the outersurface of the front shroud, and provided at its central portion with ahub mounted fixedly on the shaft, and an annular series of substantiallyradially extending blades extending between the two shrouds and adaptedin connection with drive of the impeller to draw liquid into theimpeller interior via said inlet and opening and to fling the liquidoutwards against the outer portion of the casing for discharge throughthe outlet; means on the inner surface of the front wall of the casingoperative during drive of the impeller to retard rotation of the liquidin the clearance space between the front shroud of the imshroud and thuscounteract end thrust of the impeller and shaft in the direction of theinlet.

5. A centrifugal pump adapted to displace or pump a liquid andcomprising a voiute casing embodying spaced apart front and rear walls.pro! vided with an inlet in the central portion of its front wall and anoutlet at its outer portio and having the inner face of its rear wallsmooth; a

drive shaft of less diameter than the inlet extending through the rearwall of the casing and arranged in axial relation with said inlet; aclosed variety impeller disposed in the casing and embodying a frontshroud arranged in opposed and spaced relation with the casing frontwall and provided with a central opening in communication andsubstantially sealed relation with the inlet, a rear shroud arranged inopposed and spaced relation with the casing rear wall, having the outersurface thereof of greater area than peller and the front wall of thecasing so as to increase pressure on the front shroud and thuscounteract end thrust of the impeller and shaft in the direction of theinlet; and means on the outer surface of the rear shroud of the impelleroperative during drive of the impeller to increase rotation of theliquid in the clearance space between the rear shroud of the impellerand the rear casing wall so as to decrease pressure on said rear shroudand thus further counteract end thrust of the impeller andshaft.

7. A centrifugal pump adapted to displace or pump-a liquid andcomprising a voiute casing embodying spaced apartfront and rear walls,provided with an inlet in the central portion of its front wall and anoutlet at its outer portion, and having the inner face of its rear wallsmooth; a drive shaft of less diameter than the inlet extending throughthe rear wall of the casing and arranged in axial relation with saidinlet; a closed variety impeller disposed in the casing and embodying afront shroud arranged in opposed and spaced relation with the casingfront wall and provided with a central opening in communication andsubstantially sealed relation with the inlet, a rear shroud arranged inopposed and spaced relation with the casing rear wall, having the outersurface thereof of greater area than the outer surface of the frontshroud, and provided at its central portion with a hub mounted fixedlyon the shaft, and an annular series of substantially radially extendingblades extending between the two shrouds and adapted in connection withdrive of the impeller to draw liquid into the impeller interior via saidinlet and opening and to fling the liquid outwards against the outerportion of the casing for discharge through the outlet; a rib structureformed on the inner surface of the front wall of the-casing andoperative during drive of the impeller to retard rotatlon'of the liquidin the clearance space beof the impeller to increase rotation of theliquid in the clearance space between the rear shroud and the casingrear wall so as to decrease pressure on said rear shroud and thusfurther counteract end thrust of the impeller and shaft.

DE WITT E. YATES.

